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85 dB vs 100 dB

100 dB is 15 dB louder than 85 dB — about 32× the sound energy and roughly 2.8× the perceived loudness. In practice that is the difference between heavy city traffic and a jackhammer at 15 m.

The bars show the two levels on the 0–140 dB scale. The gap looks small as a number, but on a logarithmic scale each 10 dB is a ten-fold jump in energy.

	85 dB	100 dB
Typical source	Heavy city traffic	A jackhammer at 15 m
Category	Very loud	Extremely loud
Sound pressure	0.3557 Pa	2.0000 Pa
NIOSH safe time	8 hours	15 min
Protection needed	Yes	Yes

Why 15 dB is a bigger jump than it looks

A 15 dB gap looks small written down, but decibels are logarithmic. Every 10 dB multiplies sound energy by ten and roughly doubles perceived loudness. Going from 85 dB to 100 dB therefore multiplies the acoustic energy by about 32× while your ear reports something closer to 2.8× as loud. Both statements are true — they simply measure different things.

Which one is safe?

Both levels are at or above the 85 dBA action level, so both need exposure limits. At 100 dB the safe unprotected window is only about 15 min.

Hearing protection

For anything above 85 dB, rated protection matters. Look at the NRR (US) or SNR (EU) figure — real-world reduction is roughly (NRR − 7) ÷ 2.

Electronic ear muffs (NRR 22–25)Shooting, mowing — amplify speech, block bangsLink coming soon

Reusable filtered earplugs (NRR 20)Concerts & musicians — flat attenuationLink coming soon

Foam earplugs (NRR 32)Sleep, travel, DIY — highest raw NRRLink coming soon

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The distance equivalent

One intuitive way to feel a 15 dB difference is to think in distance. Outdoors, every doubling of distance removes about 6 dB, so standing at 100 dB versus 85 dB is roughly like standing 5.6× closer to the same source. Conversely, moving about 5.6× further away would bring 100 dB down to 85 dB.

Adding the two levels together

Decibels do not add arithmetically. A 85 dB source running alongside a 100 dB source does not produce 185 dB — the correct total is 100.1 dB, calculated as 10 × log₁₀(10^(85/10) + 10^(100/10)). Because the louder source dominates, the quieter one contributes only 0.1 dB. Our decibel calculator does this for any combination.

Frequently asked questions

Is 100 dB much louder than 85 dB?

100 dB carries about 32 times the sound energy of 85 dB and is perceived as roughly 2.83 times as loud.

What is the difference between 85 dB and 100 dB?

The difference is 15 dB. 85 dB is comparable to heavy city traffic, while 100 dB is comparable to a jackhammer at 15 m.

What do 85 dB and 100 dB add up to?

Combined, two sources at 85 dB and 100 dB produce about 100.1 dB — not 185 dB — because decibels add logarithmically.

Which is safe, 85 dB or 100 dB?

Both exceed the 85 dBA action level, so both need exposure limits and, ideally, hearing protection.

See each level in detail

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Sources & accuracy. Reference levels are drawn from published data by NIOSH, OSHA, the CDC, the WHO Environmental Noise Guidelines and the American Speech-Language-Hearing Association (ASHA). Real-world readings vary with distance, room acoustics and the specific source, so treat every figure as a typical value rather than an exact constant. Last reviewed 2026-08-11.